The Control or Red Scale in Pear Orchards. 337 



THE CONTROL OF RED SCALE IN PEAR 

 ORCHARDS. 



Spray Experiments at Elsenburg during the 1920-1921 

 and 1921-1922 Fruit Seasons. 



lU F. W. Pettey, B.A., Ph.D., Entomologist, Elsenburg School 



of Agriculture. 



Red scale, Clifijaomplialus aurantii, infests not only some \!arieties 

 of pears and apples, but also many species of wild and cultivated 

 plants, particularly oranges, lemons, I'oses, grapes (generally only 

 when growing in the shade), oak, willow, and olive. Fruit growers 

 should determine which varieties in their orchards require treatment 

 for the pest. In the Elsenburg orchard, the Louise Bonne, Duchesse, 

 Forelle, Kiefter, Comice, and Beurre Hardy pear varieties are the most 

 attacked, and Williams, Winter Nelis, Bosc, and Bergamotte varieties 

 are the least infested. The fruit grower should avoid, when possible, 

 planting his pear and apple orchard near oak or willow trees, as they 

 may be a source of infestation to the fruit trees. 



The Life-history (1). — The scales are brownish in colour. The 

 adult female is about the size of an ordinary pin-head and circular 

 in shape. The adult male scale is somewhat smaller and elliptical. 

 The actual scale is not the insect, but its two shed skeletons, which 

 remain ov^er its back in the course of its development. The partly 

 to full-grown scale insect remains on the twigs and buds of the fruit 

 trees during the winter. No eggs are laid, the young being born 

 alive during the late spring and summer. They are minute, yellow, 

 and appear like granules of sulphur. They may be seen crawling 

 along very slowly on twigs, leaves, and fruit infested with this scale 

 insect, mo^^ing no faster than a few inches per hour. They become 

 stationary in a few hours to two days, do not move for the rest of their 

 life, and then the scale, composed finally of secretions from the body 

 of the insect, and parts of the two shed skeletons, forms on their backs. 

 They l)ecome adults m 2h to 31 months. It has been noted at Elsen- 

 burg that young scale insects from individuals which may have 

 escaped the winter spray have a decided tendency to migrate to the 

 fruit. It appears that the fruit of susceptible pear varieties which 

 blossom late escapes a considerable number of the migrating* young. 

 The presence of these insects on the fruit is objectionable, because it 

 deforms and disfigures, and prevents the export of the fruit. It is 

 clearly seen that this insect, which is minute, inconspicuous, and is 

 protected by a hard covering, penetrable with difficulty, requires 

 thorough spraying with high pressure to be satisfactorily controlled. 

 It is necessary to cover all parts of the tree, spraying from all sides 

 the buds, twigs, and large branches. 



